Gaskets are often used to seal mating mechanical components. In one application, a cylinder head gasket for an internal combustion engine is formed from a plurality of metallic gasket layers laminated together. In addition to providing a seal between the engine block and the cylinder head of an internal combustion engine, the metallic layers further provide structural support, as well as radial strength to resist gasket blow-out due to combustion chamber generated pressures.
Typically, the metallic layers are laminated together by welding to insure that the gasket layers remain properly secured and aligned during operation of the engine. However, welding is undesirable for a number of applications. For example, welding is a time consuming process that involves specialized tooling, thus increasing manufacturing costs. Further, due to the high weld temperatures generated, the metallic layers may become warped, thereby compromising sealing effectiveness. Additionally, weld beads formed by the welding operation may interfere with mating members before they are fully tightened together, thereby reducing the force available for sealing the gasket layers.
To avoid the difficulties associated with welding, it has been known to provide a metallic gasket with a plurality of bending strips of a first metal plate that engage holes in a second mating metal plate to connect the first and second metal plates together. While the use of bending strips is less expensive than welding, a bending strip produces localized stress loading, which may compromise gasket sealing effectiveness over time. Further, the edges of the bending strip are unprotected. Therefore, the bending strip may become accidentally dislodged from the hole or otherwise damaged. In addition, the bending strips often have limited effectiveness in gaskets that are subject to high frictional forces. The frictional forces may cause buckling and sliding of the metallic plates, thereby resulting in the bending strips becoming partially disengaged from the first plate. Thus, once again, sealing effectiveness is potentially compromised.
Another known gasket assembly includes providing a spacer ring disposed between each gasket layer. The spacer ring is formed with annular serrations on its opposite surfaces. When the gasket assembly is positioned between the cylinder head and the engine block, the compression forces therebetween cause the serrations of the spacer plate to deform and grip the gasket layers to hold the gasket layers together and increase sealing effectiveness. However, there is no means for positively locking the plates to one another when significant vibrations result from engine operation. Thus, the frictional forces deforming the spacer ring serrations against the gasket layers may be overcome such that the gasket layers slide apart from one another during engine operation, resulting in reduced sealing effectiveness and possible engine damage. Further, there is no mechanism for insuring proper gasket layer alignment prior to compression.
Therefore, there exists a need for effectively locking gasket layers together such that frictional forces do not compromise the alignment or sealing effectiveness.